Backing-off attachment for engine-lathes.



No. 637,887. Patented nec. 3, 190|; v

l w. T. s. JoHNsoN.

BACKlNG-DFF ATTACHMENT FDH4 ENGINE LATHES.

(Application led Aug. 2, 1901.)

3 Sheets-Sheet I.

(No Model.)

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@tbm/nuto Patented Dec." 3, IQUI.

W. T. S. JOHNSON. BACKING-OFF ATTACHMENT FDR ENGINE LATHES.

(Application filed Aug, 2, 1901.)

3 Sheets-Sheet 3.

(No Model.)

atmmw NITED STATES .armi Prien.

WILLIAM T. S. JOHNSON, OF CINCINNATI, OHIO.

BACKiNe-OFF ATTACHMENT Foa ENGINE-LATHES.

SPECIFICATION forming part of Letters Patent No. 687,887, dated December3, 1961. Application led AugustZ, 1901. Serial No. 70,569. (No model.)

To all whom, t may concern-.-

Be it known that I, WILLIAM T. =S. JOHN- SON, a citizen of the nitedStates of America, and a resident of Cincinnati, in the county ofHamilton and State of Ohio, have invented certain new and usefulImprovements in Backing-Off Attachments for Engine-Lathes, of which Jthefollowing is a specification.

My invention relates to a backing-0F attachmentfor engine-lathes.Backing-off is understood in the class of machines to which my inventionrelates to mean some provision by which a tap or milling-tool has itsperimeter back of its cutting edge or edges inclined toward the axis ofrotation, thus leaving a clearance back of the cutting edge, so as toprevent burning or unnecessary frction,as would occur if the wholeperimeter were formed concentric to the axis of revolution.

My invention is especially designed for backing-off taps whethercylindrical or tapered, and while it may be applied 'to any well-knownengine-lathe it is believed it would be better understood if illustratedand described as applied to the well-known J ohnson taper lathe, whichis shown and described in Letters Patent No. 503,088, dated August 8,1893.

Referring to the drawings, in which like parts are indicated by similarreference-letters Wherever they Occur throughout the various views,Figure l is a plan view of so much of ataper lathe with my improvementsattached as is necessary to illustrate my invention. Fig. 2 is avertical transverse sectional view of the same, taken through line fn, nof Fig. l. Fig. 3 isa longitudinal sectional view on line y y, Fig. 2,and line z c, Fig. 4.. Fig. 4 is a transverse sectional View, on a largescale, through line .e z, Figs. l and 3. Fig. 5 is a similar View toFig. 4. upon the same scale, but taken through line v fu, Figs. l and 3.Fig. 6 is a detail view, in longitudinal section through line z c, ofthe attachment on the same scale as Figs.4 and 5. Figs. 7, 8, and 9 aredetached detail views in perspective of the parts of the Johnson taperlathe modified to adapt it to the use for backing-off taps or similartools used by machinetool makers, Fig. 7 being a viewof the guidebar,Fig.'8 an intermediate attachment between it and the restraining-bar fora taper attachment for engine-lathes, and Fig. 9 the restraining-barmodified to adapt it to backing-off taps and similar tools,whethertapered, cylindrical, or other desired shape. Fig. l() is a view, partlyin end elevation and partly in section, of one of the bearings which aresecured to the opposite ends of the restraining-bar, Fig. 9. Theseviews, Figs. 7 to l0, inclusive, are to a still larger scale than thepreceding views.

Referring to the parts, A represents the lathe-bed, and B the carriagemounted to slide thereon between the customary head and tail stocks.

C is the tool block or holder, mounted to slide on the carriage acrossthe lathe. The tool block or holder is coupled to the crossfeed screw Dby a nut D. The screw D is plain or Unthreaded at its forward end and issplined in its front bearing, so that if it slides with the tool-blockwhen said block is controlled by the taper attachment which is supportedby bracket E, which bracket is secured to the rear edge or may be madeintegral with the carriage, the tool-block is under control of thecross-feed screw at all times to adjust the cutting-tool with relationto the axis ot' the lathe-spindles or the Work acted upon. The bracket Ehas a longitudinal way toguide the restraining-bar F of the taperattachment upon which the angular adjustable guide-bar G is pivoted.There is tted to slide on the rib ot' the guide-bar the slipper H, whichis coupled to the tool-holder C, which carries the stud K, in which therear `end of the cross-feed screw is journaled between collars whichprevent endwise movement of the screw independent of the bar I. Therestraining-barF has its end turned atf to enter a notch in thebed-clamps L,y by which The parts above referred to are well knownV andneed not therefore be more specically described excepting only themodification of the bracket E and restraining-bar F, which adapts thetaper lathe to be changed to back- ICO off taps or similar tools whendesired without removing any of the parts or interfering in any Way withthe functions of the Johnson taper lathe when the backing-off attachmentis disconnected. These changes will now be described in connection withmy backing-o attachment.

It is well understood and is apparent from the foregoing descriptionthat the guide-bar G is pivoted and angnlarly adjustable upon therestraining-bar F, that they move t0- gether when the clamp L isreleased, and rest together when the clamp L is fixed to the lathe-bed.This relation of the guide-bar G and restraining-bar F is followed in mybacking-off' attachment; but the frame or support for the backingoffattachment M (see Fig. 8, Sheet 3) is interposed between the guide-bar Gand restraining-bar F, and this interpositon requiressome modificationof the bracket E and bars F and G. In order to get my backingoffattachment in my taper lathe in as compact a form as possible withoutinterfering with its other functions, I conceived the following changesto be essential, made those changes, put them into practical use, andfound they attained the results I contemplated when I first conceivedthe invention:

In order to obtain the space between the bars G and F for theinterposition between them of the support for the backing-offattachment, the bottom or base of the foundation-plate of the bracket Eis dropped somewhat lower than in my former patent andthe guidewayformed in the foundation to receive the rib on the under side of the barF, the parts being merely a reversal of those shown in my former patent.The bar F being correspondingly dropped, the inturned endf of the bar iselevated to engage the notch in the clamp L. The bar F being separatedfrom the guide-bar G by the interposition of the support M of thebacking-off attachment required further changes in both bars F and G, sothat they would retain fixed relation to each other after the guide-barG was given its proper angular adjustment. These changes consist inproviding the upper face of the bar F with dovetail blocks f to engagedovetail ways in the under side of the support M. Upon the top of thesupport M is fixed the foundation-plate m, which has anupwardly-projecting pivot-pin m to enter a hole in the under side of theguide-bar G, thus practically pivotally connecting the guide-bar G andrestraining-bar F to act as in all modern taper lathes. Therestrainingbar F, guide-bar G, and intermediate support M are cored out,as shown in the drawings, to reduce the weight of the castings Withoutweakening them for effective work and also to provide ways for thepassage of the shaft for operating the backing-off attachment.

To impart a reciprocating movement to the support M, and through it tothe tool-block while the carriage is traveling on its ways on lthelathe-bed, I have provided a shaft N, which is journaled in bearings nn', secured v earnest? to the rear of the lathe-bed at each end, whichshaft passes freely through the taper attachment below the guide-bar Gand through the cored-out portion of the support M, restraining-bar F,and the semicircular part of the interposed member M. The shaft N,opposite each end of the arms m2 of the member M, is provided witheccentrics n2, which are secured to the shaft by splines, which permittheir movement longitudinally on the shaft and compel their rotationwith it. Upon the eccentrics n2 are fitted similar eccentrics n3, whichhave projecting from their opposite faces clutch members to engagesimilar clutch members n4, which project from sliding collars N', whichcollars are splined upon the eccentrics n2. The purpose of thisarrangement is to adjust the outer eccentrics with relation to eachother when the clutches are disconnected to limit the movement in eitherdirection of the support M of the backing-olf attachment when theclutches are thrown into engagement. Thus when the highest points rofthe inner eccentrics are opposite the lowest points of the outereccentrics the perimeters of the outer eccentrics are concentric to theaxis of the shaft N and no movement in a transverse direction isimparted to the member M. When, however, the highest points of both setsof eccentrics coincide, the extreme limit is attained. By adjusting theeccentrics between these limits the backing-off attachment may be set toany angle of adjustment to form taps of any size or kind desired.

The backing -off attachment is connected to the eccentrics n3 by arms O,which are journaled at their outer ends on stud-shafts 0, secured in thearms m2 of the support M. The inner ends of these arms are formed ineccentric-straps to lit the eccentrics n3. These straps haveoutwardly-projecting flanges to receive tightening-bolts o? fortightening the straps on the eccentrics to compensate for wear.

The clutches have grooved hubs to receive yokes p, which are actuated bya shaft P, which shaft is journaled in bearings f2,

secured at each end'of the member F, thel shaft being prevented frommoving longitudinally by collars on the shaft in the usual manner. Theinner ends of the yoke-arms are tapped, the one with a right and theother with a left hand thread to engage right and left hand threads onthe shaft I). Thus when the shaft is turned in one direction by thehand-Wheelp' the clutches are simultaneously disengaged from theeccentrics n3, and a reverse movement of the hand-wheel after the angleof the eccentrics is adj usted throws the clutches into engagement. Theyoke-arms which enter the grooves in the clutch-hubs are armed withfriction-rollers p2.

The shaft N is driven by pinion n4, which meshes With one of the pinionsof the driving mechanism at the head-stock of the lathe. The speed ofthe shaft may be varied in the IOO IIO

usual manner relative to the speed of the livespindle or lead-screw. Theshaft N has secured upon it between its bearing f3 in the plate F' andthe head-stock a hand-wheel a5. This hand-wheel has an extended hubfitted with a set-screw a6, which makes the handwheel also ashaft-coupling. The separated part of shaft N enters this hub and iscoupled to or disengaged from the hand-Wheel by tightening or looseningthe screw n. The purpose of this arrangement is twofold: First, when theclutches are disconnected the set-screw is loosened. Then-the hand-wheelis used to adjust both sets of outer eccentrics upon the innereccentrics to fix the throw of the backingo-attachment support M. Whenthe eccentrics are given the proper angular adjustment, the set-screwnut n is tightened on the shaft N within the hub. Second, when it isdesired to wholly disconnect the backing-off attachment the set-screw nsis simply loosened, thus allowing the en'd of shaft N to revolve freelywithin the hub of coupling and hand-wheel a5, the part of the shaftcarrying the eccentrics remaining idle, as they would if the pinion n4were removed from the end of shaft N.

Assuming that the blank for a taper tap is l to be formed and backed offpreparatory to having the radial grooves milled in it to presentcuttingedges, which may be sharpened by grinding the radial faces of thecutting edges, the operation may be briefly described as follows:Disconnect the shaftNby loosening screw ne, then adjust the guide-bar Gto the desired angle, and tighten the bed-clamp L to the bed of thelathe. When the lathe is started, the desired taper is turned, preciselyas described in my former patent. Then by means of the hand-wheel pseparate the clutch members N', and by means of handwheel W5 adjust theeccentrics to give proper throw to the backing-off attachment M. Whenproperly adjusted, turn the hand-wheel p in the reverse direction,coupling the clutch members, tighten the set-screw n, and the blank yforthe tap (the proper tool of course being,r fixed in the tool-block) willthen cut the threads and back them off at the same time. Of course ifthe clamp L is released the blank will be first turned to a cylindricalform if the set-screw ne is loosened, and when the set-screw istightened up to put the backing-o attachment in operation the threadswill be cut on the cylindrical form and. proper] y backed o, the same asbefore described for the taper form.

In machines of this kind the live-spindle and the lead-screw are both unat a low speed to attain the best results, and the shaft N should maketwo, three, or` more revolutions to one revolution of the live-spindle,depending upon the number of longitudinal grooves or cutting edges to beformed upon the tap or other cutting-tool; but it is not necessary togive any detail description of this, because every lathe is built withchange-gear, and every mechanic skilled in operating a known forms ofmachines or lathes which are now and have been for a long time in publicand common use and described in numerous Letters Patent both before andsince the date of the Johnson patent of August 8, 1893.

What I claim is 1. In an engine-lathe the combination of the carriage,the tool-block fitted to slide thereon and having a bar extending fromthe rear end of the carriage, a shaft journaled at the rear of thelathe-bed and driven by suitable gearing mounted in the head-stock,eccentrics splined upon said shaft to revolve with it while permittinglongitudinal play along said shaft, and suitable connections as shown tocouple said eccentrics to the rearwardly-extended bar of the tool-blockto impart a reciprocating movement to the toolblock independent of thelead or cross-feed screw, substantially as shown and described.

2. In an engine-lathe the combination of the carriage having a dependingbracket at its rear, the tool-holder mounted to slide upon the saidcarriage and having a rearwardly-extending bar projecting over thedepending carriage-bracket, a pivoted guide-bar capable of angularadjustment with relation to the ICO travel of the carriage, a slidingblock or shoe to slide upon said guide-bar and connected to therearwardlyextending bar of the toolblock, a transversely-sliding supportupon which the guide-bar is pivotally mounted, a restraining-bar uponwhich the transverse support is mounted to slide transversely saidrestraining-bar being fitted to slide longitudinally in the bracketconnected to the carriage and having an upturned end to enter a notch inthe bedclamp, the notched bedclamp capable of being clamped to orreleased from the lathe-bed, the shaft journaled at the rear of Thelathe-bed at each end and connected to suitable gearing mounted in thehead-stock, the eccentrics splined upon said shaft, and eccentricstrapsand arms connecting the eccentrics with the transverselysliding supportfor the purpose of imparting a limited reciprocating movement to thetoolblock independent of the lead or cross-feed screw, substantially asshown and described.

3. In combination with a taper lathe of the character described thelathe-bed, the carriage, the tool-holder mounted to slide thereon andhaving a bar connected to. it extending over the rear end of thecarriage, the bracket depending from the carriage and having a barfitted to slide longitudinally in said bracket,

IIO

said bar having an upturned end to engage a bed-clamp, the bed-clampnotched to receive the upturned end of the said sliding bar and having aclam ping-screw to clamp it to or release it from the bed, anintermediate sliding member iitted to travel longitudinally with saidbar but capable of being reciprocated upon said bar, a block mounted onsaid reciprocating member and having an upwardlyprojecting pivot, theguide-bar angularly adjustable on said pivot, the shoe fitted to slideupon said guide-bar and pivotally connected to the rearwardly-extendingbar of t-he toolholder, a shaft journaled in bearings at the rear of thelathe and having eccentrics splined upon it, eccentric-straps and armsconnecting said eccentrics to the intermediate sliding member wherebythe tool-block is given a reciprocating movement independent of themovement imparted to it by the guide-bar with its connections,substantially as and for the purpose set forth.

4. In a taper lathe of the character described the carriage, the bracketdepending from the rear edge thereof and having in its base a guidewayfor the restraining bar, the restraining-bar fitted to slide in said wayhaving an upturned end to engage a notch in the bedclamp and transversedovetailed blocks to furnish guides for the reciprocating support forthe backing-off attachment, the backingoff attachment having dovetailedways on its under side to it said blocks, a support on its upper sidehaving a pivot-pin to enter a hole in the guide-bar,longitudinally-extended perforated arms to receive stud shafts uponwhich the arms by which the backing-off su pport is actuated arejournaled, the notched bed-clamp to receive the upturned end of therestraining-bar to lock it to or release it from the lathe-bed whendesired, the guide-bar pivoted upon the backing-off attachment, theslip-block fitted to slide on the guide-bar, the tool-block fitted toslide on the carriage and having a rearwardly-extending arm connected tothe slipper, the longitudinal shaft journaled in bearings at the rearedge of the lathe-bed, a pinion secured on said shaft and meshing withthe gearing of the head-stock whereby the said shaft is actuated,eccentrics splined upon said shaft, arms pivoted upon the stud-shafts inthe arms of the reciprocating backing-off support and havingeccentricstraps engaging said eccentrics, and the cross-feed screwcoupled to the sliding toolblock and moving with it under control of theslipper of the taper attachment whereby the tool-block is moved relativeto the work parallel with the guide-bar and at the same 5. In a taperattachment for lathes the carriage having a depending bracket at itsrear, the restrainingbar fitted to slide in said bracket cored out uponits upper face and cease? having transverse dovetailed blocks and an endturned inwardly and upwardly, the support for the backing-off attachmenthaving ways on its under side to receive the blocks on the upper face ofthe restraining-bar, an upwardly-projecting pivot to enter the guidebar,the guide-bar pivoted on said support and capable of angular adjustment,and a shoe Iitted to slide on said bar and capable of being coupled tothe sliding tool-block by which combination of said parts the taperattachment is also adapted to serve as a backing-off attachment withoutinterfering with the functions of the lathe or taper attachment when thebacking-off attachment is disconnected, substantially as shown anddescribed.

6. In a taper attachment for engine-lathes the combination of a supportfor the backingoff attachment interposed and fitted to slidetransversely between the restraining-bar and guide-bar of the taperattachment, a shaft journaled in bearings at the rear of the lathebedpassing through the taper attachment and provided with gearing torevolve said shaft, inner eccentrics splined upon said shaft, outereccentrics capable of adjustment upon the inner eccentrics for thepurpose of regulating the throw of the backing-off attachment, saidouter eccentrics having laterallyextending clutch members to engageopposite clutch members extending from sliding collars upon said shaftto lock the inner and outer eccentrics together when the desiredadjustment is made, said collars having grooved hubs and yokes fittingthe grooves in said hubs to throw the sliding clutch members into andout of engagement with the eccentrics, eccentric-straps fitting saidouter eccentrics and having arms connected to the backing oifattachment, substantially as shown and described.

7. In a backing-off attachment for taper lathes the combination of theeccentrics, the outer one of which is provided with clutch members, thesliding clutch members to engage said eccentrics, a shaft journaled inbearings secured to the restraining-bar and held against longitudinalmovement in its bearings, said shaft being threaded at each end with aright-hand screw upon one end and a left-hand upon the other, thehandwheel for revolving said shaft in either direction, yoke-armsadapted to engage the screwthreads on said shaft and bifurcated at theirinner ends to enter grooves in the clutch members whereby a movement ofthe handwheel in one direction simultaneously disengages the clutchesfrom the eccentric and when moved in the opposite direction brings theclutches into engagement with the clutch members on the eccentrics,substantially as hereinbefore set forth.

8. In a backing-off attachment for taper lathes in combination with theeccentrics for actuating the backing-off attachment and the slidingclutch-collars for engaging clutch IOO IIO

to the gearing of the head-stock by tightening the screw in the hub ofthe coupling and hand-Wheel, substantially as shown and described.

WILLIAM T. S. JOHNSON.

Witnesses:

'W. F. MURRAY, EMMA LYFORD.

